Wheel rim



Patented Jan. 14, 1936 UNITED- STATES- j PATENT OFFICE Herman Johan van Rayon. Horde in :Westi'alia, Germany No Drawing. Application August 15, 1032, Serial No. czacsa In Germany s m 4, 1031 column.

than that of eutectoid steels, containing 0.9% of carbon.

It has also transpired that, in general, the resistance to abrasion of lamellar pearlitic eutectoid steels is determined by the content of doublecarbide formers ,in the cementite lamella. of the pearlite, and that the manganese employed, as double-carbide former, in previous experiments can be wholly or partially replaced by chromium, molybdenum, tungsten and vanadium, with good results. The amount of the other metals, substituted for, or used in association with the manganese. is adjusted so that the carbon content of the eutectoid steel lies between 0.68 and 0.77%, the manganese content being, for example, between 0.40 and 0.85%, the chromium between 0.30 and 0.80%, the tungsten between 0.25 and 0.70%, the molybdenum between 0.22 and 0.65%, and the vanadium between 0.18 and 0.60%.

Further experiments showed unexpectedly that the already high resistance to abrasion o! eutectoid steels containing the aforesaid double-cab bide formers, can be further increased by raising hard-wearing eutectoid steels, hitherto produced by applicant, lay between the usual limits of 0.15 to 0.30% for carbon steels, of the same tensile strength, chilled with silicon alone. Slightly increasing the silicon content, for example by a little more than 0.05%, resulted'in an unexpectedly high increase in the resistance to, abrasion, which can be still further heightened by further addition of silicon. In such case, also, the presence of a purely lamellar pearlitic structure is essential to success since, as is known, a eutectoid steel does not necessarily exhibit a lamellar structure after cooling. .Steels, on the contrary, that contain chromium, molybdenum, tungsten and vanadium in addition to manganese, tend to form sorbitic pearlite in normal cooling. Thus the object of this invention is a wheel rim. and similar articles offering high resistance to abrasion and exhibiting a purely lamellar pearlitic structure composed of a steel with a carbon content beto abrasion which is not only considerably higher than that of the normalized steels, but also higher;

the silicon content. The silicon content of the tween about 0.65 and 0.78%, a silicon content between about 0.40 and 0.80% and comprising at least one of the following double carbide formers: manganese between about 0.40 and 0.85%, chromium between about 0.30 and 0.80%, tungsten between about 0.25 and 0.70%, molybdenum between about 0.22 and 0.65%, vanadium between about 0.18 and 0.60%, the balance comprising substantially iron, the sum of said double carbide formers being so proportioned that the composilamellar pearlitic structure in the finished articles. Y

The-following examples represent the composition of steels produced in accordance with the invention:- r

0 Mn Bi Cr W Mo Va The favourable eifect of higher silicon contents is evident from the following figures:-

Abrasion test in the Mohr.& Federhafi tester, under the following conditions:-

The experiments showed that, by increasing the silicon content above the ordinary limits, the wear under the specified test conditions is below the minimum, namely 300 mgrms. of that of ordinary hard-wearing steels in the best instances." I

In the case of eutectoid steels containing certain percentages of carbon, which will be referred to hereinafter, the experiments also indition is eutectoid, the steel having also purely cated that silicon, in association with doublecarbide formers, produces a particularly high resistance to abrasion, and this was not hitherto known. The favourable effect of higher silicon contents on the resistance to' abrasion of lamellar pearlitic .eutectoid steels containing doublecarbides is probably attributable to the modification in the composition of the cementite lamellm. As is known, the silicon in steel partly passes into the cementite lamellar of the pearlite. Accordingly, higher percentages of silicon also lower the carbon content of the pearlite. Whether the silicon exists in the cementite, as iron silicide or silicon carbide, or as doubleor poly-carbide, has not been definitely establlshed. The fact remains, however, that applicant was able to detect an. increase in the resistance to abrasion with increasing silicon content. It is hardly possible to specify the upper limit of the addition 01 silicon. This will be determined, on the-one hand, by the capacity of the cementite for absorbing silicon, and on the other hand by the decomposition of the cementite into carbon (graphite, temper carbon) and ferrite, occuring with high silicon contents and slow rates of cooling. For the production of wheel rims, rails, pinion's, spindles, and the like, silicon contents of 0.35 to 0.80% have proved favourable. In this connection, the experiments have shown that, with rising silicon content, the carbon content can be lowered to 0.65%, it being, of course, necessary to adjust the content of double-carbide formers, such as manganese,

chromium, tungsten, molybdenum and vanadium, so that a eutectoid steel is obtained in each case.

Example nese, term-chromium, ferro-tungsten or ferrovanadium is added to the molten metal in such quantities that, after the succeeding addition of ferro-silicon, to an extent that will give a silicon content of 0.35 to 0.80% in the finished steel, a eutectoid steel is obtained. The steel is then heated and shaped in the usual manner into the specified articles, but the rate of cooling the finished products is regulated, in a simple manner, by insertion in a cooling stove, covering up or packing in piles,'so that the finished article exhibits a purely lamellar pearlitic structure.

I claim:

1. Wheel rims and similar articles ofierim; high resistance to abrasion and exhibiting a purely lamellar pearlitic structure, composed of a steel with a carbon content between about 0.65 and 0.78%, a silicon content between about 0.40 and 0.80% and a manganese content between about 0.40 and 0.85% and comprising metal from a group of the double carbide formers: chromium between about 0.30 and 0.80%, tungsten between about 0.25 and 0.70% and molybdenum between about 0.22 and 0.65%, the balance comprising substantially iron, the sum of said double carbide formers being so proportioned that the composition is eutectoid, the steel having also a lamellar pearlitic structure in the finished articles.

2. Wheel rims and similar articles ofiering high resistance to abrasion and-exhibiting a purely lamellar pearlitic structure, composed of a steel with a carbon content between about 0.65 and 0.78%, .a silicon content between about 0.40 and 0.80%, a manganese content between about 0.40 and 0.85% and vanadium between about 0.18 and 0.60%, and comprising metal 'from a group 'of the double carbide formers:

chromium between about 0.30 and 0.80%, tungsten between about 0.25 and 0.'10% and molybdenum between about 0.22 and 0.65%, the balance comprising substantially iron, the sum of said double carbide formers being so proporfinished articles.

HERMAN JOHAN VAN' ROYEN. 

